A predicable demand for data, and corresponding increase in data delivery capacity, has been observed for at least the last 50 years and has come to be known as Cooper's Law. Cooper's Law states that the total capacity will double about every 30 months. More recently, this has been closer to doubling every year or two. There are many incremental technology advances taking place in air interfaces and in networks that are expected to provide meaningful gains, but for the predicted demand for mobile data a decade from now, only two main synergetic strategies emerge as the technologies capable of delivering this huge demand.
One such strategy is the use of smaller and smaller cells. “Small cells” implies an increased spatial reuse of the same spectrum and has been a conceptually simple way to achieve greater capacity over the last few decades. Using low-power nodes may be one of the ways to cope with mobile traffic explosion, especially for hotspot deployments in indoor and outdoor scenarios. A low-power node generally means a node whose Tx power is lower than macro node and BS classes, for example Pico and Femto eNB may be both applicable.
Another strategy is the use of additional spectrum, for example 3.5 GHz and higher frequencies. There is potential for large bandwidth channels to be available in high frequency carriers. A synergetic effect may be exploited at higher frequencies that is not possible in lower-frequencies (for example, below 2 GHz), as there may be the potential of much greater spatial reuse.
In order to close the link budget for millimeter wave (mmW) communications, highly directional antennas may be needed. Highly directional antennas may make the transmissions highly contained, as transmitted energy is concentrated on the intended receiver (e.g., increasing signal strength), while radiating little in other directions (e.g., reducing the likelihood that the transmission will cause much interference for unintended receivers). This may help address inter-cell interference in small cells. Since there may be a low probability of interference in the first place, there may be less of a requirement for complicated inter-cell interference mitigations techniques. In the mmW spectrum, there may be potentially large amounts of spectrum that could be made available (e.g., 60 GHz unlicensed spectrum alone may be about 7 GHz (e.g., depending on country). There may be potentially more that could become available either as licensed, lightly licensed, or unlicensed spectrum.